| // Regression test for #55756. |
| // |
| // In this test, the result of `self.callee` is a projection `<D as |
| // Database<'?0>>::Guard`. As it may contain a destructor, the dropck |
| // rules require that this type outlivess the scope of `state`. Unfortunately, |
| // our region inference is not smart enough to figure out how to |
| // translate a requirement like |
| // |
| // <D as Database<'0>>::guard: 'r |
| // |
| // into a requirement that `'0: 'r` -- in particular, it fails to do |
| // so because it *also* knows that `<D as Database<'a>>::Guard: 'a` |
| // from the trait definition. Faced with so many choices, the current |
| // solver opts to do nothing. |
| // |
| // Fixed by tweaking the solver to recognize that the constraint from |
| // the environment duplicates one from the trait. |
| // |
| // compile-pass |
| |
| #![crate_type="lib"] |
| |
| pub trait Database<'a> { |
| type Guard: 'a; |
| } |
| |
| pub struct Stateful<'a, D: 'a>(&'a D); |
| |
| impl<'b, D: for <'a> Database<'a>> Stateful<'b, D> { |
| pub fn callee<'a>(&'a self) -> <D as Database<'a>>::Guard { |
| unimplemented!() |
| } |
| pub fn caller<'a>(&'a self) -> <D as Database<'a>>::Guard { |
| let state = self.callee(); |
| unimplemented!() |
| } |
| } |
